<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN">
<style type="text/css">
.multicol {
  margin: 1em;
  border: solid silver;
  width: 300px;
  -moz-column-width: 100px;
  -moz-column-gap: 0;
  height: 100px;
}

.float {
  float: right;
  width: 15px;
  background: aqua;
  height: 250px;
}
.L {
  float: left;
}

.container {
  width: 100%;
  background: red;
}

.clear {
  clear: left;
  border-bottom: solid orange;
  background: red;
}
</style>

<p>The orange line should be halfway down the third column
(immediately after the end of the aqua lines).

<div class="multicol">
  <div class="container">
    <div class="float L"></div>
    <div class="float R"></div>
  </div>
  <div class="clear"></div>
</div>
